IINSKEEP: That's the sound of people on Washington D.C.'s National Mall, this morning, looking up as the shuttle Discovery past low over head. It is on the back of a 747 airplane, making a final bow, on its way into its final retirement at a museum. And I have to confess, people across Washington D.C. have been watching it as it circles the nation's capital, this morning. People are on the roof of this building, NPR headquarters. I was up there just a little while ago. Quite a view. NPR's Nell Greenfieldboyce has been watching from the Mall. And Nell, what have you seen?

Yeah.

NELL GREENFIELDBOYCE, BYLINE: Well, we've had an incredible view down here. I'm standing between the capitol building and the Washington Monument, sort of right next to the old Smithsonian Castle building. And we had an incredible view as the plane with its shuttle circled around the Mall a couple times, right over the capitol building, right past the Washington Monument. Right over the little carousel that's down here at the National Mall, that kids might have ridden on. It's, um - it was - lots of crowds across the Mall, scattered people. There were, clearly, tourists, groups of school children had come. There were a lot of people who were, you know, federal workers, wearing there name tags, who just walked over to see the sight. And they got, really, an incredible view.

IINSKEEP: And it is just - I've got to say, it seems quite low. I guess, maybe it seems lower than it is, 'cause it's such a huge jetliner and such a huge shuttle on its back. But still, a very low flight over D.C.

GREENFIELDBOYCE: Well, it's something that people here are going to remember for a long time, I bet.

IINSKEEP: And the kind of thing that almost turns you in to a little kid again, looking at that.

GREENFIELDBOYCE: There were plenty of kids here, and I think they were doing the screaming for all of us.

IINSKEEP: OK. So let's remember what is actually, physically happening here. The shuttle flew up, this morning, from Florida. By the way, we're waiting for it, now, to land at Dulles International Airport. Where's it going?

GREENFIELDBOYCE: Well, it's going to a facility that the Smithsonian's National Air and Space museum runs, that's right near that airport. It's going to be formerly installed on Thursday. They're going to have a ceremony there. And as you may recall, that building actually already has a prototype shuttle that's going to be swapped out. That's called Enterprise. And it's going to be put on the plane, and it's going to be shipped up to New York City. And basically - well, next week it goes to New York City and they're planning to do a, sort of, similar flyby up there. And then in June, that prototype shuttle, Enterprise, will be put on a barge, and basically, is going to be floated up the Hudson River, past the Statue of Liberty, to go to a museum there in New York, called the Intrepid Museum, which is basically an aircraft carrier parked next to Manhattan.

IINSKEEP: And there are other shuttles that are going other places.

GREENFIELDBOYCE: That's right. There's two more. There's Endeavor, it's going to the California Science Center - That's out in Los Angeles. And so, they'll be flying it out there on the jumbo jet. And then, it's going to make its way through 12 miles of streets - the city streets. So that will be, sort of, like a parade and another opportunity for the public to see the shuttle. And then there is Atlantis, which is going to be staying in Florida. It doesn't have as far to travel, it's just going next door to the Kennedy Space Center's Visitor's Center.

IINSKEEP: We're talking with NPR's Nell Greenfieldboyce, one of many people at the National Mall, in parks, on rooftops in Washington D.C. or nearby, watching as the shuttle Discovery - almost like riding on a horse, on the back of this 747 - flew low over the nation's capital today, on its way into retirement. And how will these shuttles actually be displayed, what kind of access will people have to them?

GREENFIELDBOYCE: Well, people, unfortunately, are not going to be able to climb inside and pretend to fly the shuttle. The hatch to get inside is just too small, you couldn't squeeze millions of people through every year. Different places are going to display them different ways. In Florida, they plan to, sort of, suspend the shuttle and make it look like it's in flight around the Earth. They're going to have the payload bay doors open. And in California, they hope to have it upright, like it's on the launch pad, about to take off. And that, of course, creates structural, engineering challenges because California is a seismic zone, so they have to worry about earthquakes.

IINSKEEP: Wow, OK. Well, Nell, thanks very much.

GREENFIELDBOYCE: Thank you.

IINSKEEP: That's NPR's Nell Greenfieldboyce. She is standing on the National Mall in Washington D.C. The shuttle Discovery, on the back of a 747, made a final pass over the nation's capital just a short time ago. Transcript provided by NPR, Copyright National Public Radio.